package panda.query.util;

import java.util.List;

import panda.query.scan.Scanner;
import panda.query.struct.Attribute;
import panda.query.struct.Constant;
import panda.query.struct.NullConstant;

/**
 * 
 * @author Tian Yuan
 */
public interface Comparator {

	public int compare(Scanner a, Scanner b);
		
}
